Thermophysical dispersion properties of agricultural biomass particles in ethylene glycol

Abstract

• Sunflower stalks as biomass were used to produce particles by hydrothermal carbonization and treatment in the oven with inert atmosphere. • Dispersions were prepered by suspending particles in etylene glycol as base fluid by two step method. • The density, viscosity and thermal conductivity of the dispersions increase with mass concentration of particles. • The dispersions could be potentially useful for heat transfer applications. The purpose of this paper is to examine the thermophysical dispersion properties of agricultural biomass particles in ethylene glycol as a base fluid. The following thermophysical dispersion properties were considered: density, viscosity and thermal conductivity. The aim of the research was to develop a new class of dispersion which could be a sustainable alternative to nanofluids. Dispersions with different particle mass concentrations (0 wt%, 1 wt%, 5 wt% and 10 wt%) were investigated at a temperature of 20 ⁰C. Sunflower stalks, as agricultural biomass, were used to produce particles. The dispersions considered were prepared using the most widely applied two-step method, which involves the hydrothermal carbonization of the biomaterial (which was subsequently heat-treated in a nitrogen atmosphere furnace) and the particle dispersion in ethylene glycol. It was found an intensity of around 30% of particles with a mean peak diameter of 415.2 nm. The rheological results obtained indicate that the dispersions had Newtonian behavior (>20 s −1 ). Particle mass concentrations were found to increase the density, viscosity and thermal conductivity of the dispersions. According to the performance evaluation criteria considered, the dispersions obtained could be useful for heat transfer applications.